Determining sustainable water resource utilization rates is an important problem faced by regulatory agencies all around the world. One of the key parameters in determining accurate water budgeting schemes is the rate of water resource replenishment, or ‘recharge’ in groundwater systems. Fundamental questions regarding groundwater recharge include: What is the source of recharge? What is the spatial distribution of recharge? What is the annual average recharge rate, from potentially disparate sources in disparate areas? Answers to these questions can be gained through combining physical and chemical hydrogeological research tools, including stable isotopic compositions. Land-use intensification, including significant increases in dairying, has placed a priority on developing water resource management practices throughout New Zealand. Here we present the first compilation of delta oxygen-18 and delta hydrogen-2 values from individual precipitation events, local surface waters, depression springs, and groundwaters from the greater-Christchurch area. A variety of analytical methods were used in an effort to evaluate the potential use of stable isotopic compositions as tracers of surface-groundwater interaction in the local hydrologic cycle. The results of this thesis found the isotopic variability of Christchurch precipitation to be highly varied. Back-trajectory analysis of single precipitation events exhibit pathways arriving from three principal sources: the Southern Pacific Ocean, the Tasman Sea, and the Tropical Pacific Ocean. Separately, delta oxygen-18 and delta hydrogen-2 values values from these sources show three distinct local meteoric water lines, which are determined to be largely affected by the environmental conditions present in these areas at the time water vapour formation. Intra-storm variation of extra-tropical cyclones support these findings as significant changes in deuterium excess as moisture sources change with southward movement of the low pressure system. Three line-conditioned tests were subsequently developed to compare the relationship between monthly surface rainfall, surface water, and groundwater samples to the respective moisture origins. Surface rainfall, rainfall infiltration, surface waters, and groundwaters all exhibit the least amount of deviation from the Southern Pacific Ocean local meteoric water line. These observations suggest the principle moisture source to Christchurch to be from west-south westerly flow from the mid-latitudes. However, these similarities do not make partitioning their relative contributions to the groundwater system easy. Previous physical and isotopic investigations have shown the dominant sources of recharge to the Christchurch Groundwater System (CGS) are alpine rivers and local precipitation of which there is statistically significant difference with respect to delta oxygen-18 values. A binary single-isotope mixing model allows for quantification of the relative contributions of alpine river and precipitation derived inputs to local depression springs. The isotopic model indicates that approximately 80% of spring discharge was derived from alpine rivers, in good agreement with recently published physical mass balance model results. Deep groundwater flow paths however show groundwater to flow from the Central Canterbury Plains to the CGS. Potentially including losses from the upper Waimakariri River reaches. If included, this places a net recharge amount to the CGS water budget, which if using losses from only the lower Waimakariri River, there is a net loss. Losses from the upper reaches and subsequent groundwater flow into the CGS are likely as there have been no observed declines in groundwater levels even though there is currently a net loss by only using recharge components within the CGS. Ultimately, recharge from groundwater movement from the Central Canterbury Plains may play significant role; however, a much more sophisticated geochemical model is needed to test these theories and determine contributions. This research demonstrates the utility of stable isotopes as tracers of hydrogeological processes, particularly in shallow groundwater, and their potential contributions to the water resource allocation decision making process.

This study presents an overview of lightning formation and the correlations seen with soil moisture slope along with potential of tornadic thunderstorms. Three moisture classes (large, marginal, small) were created using soil moisture observed during three tornado outbreaks (June-02-1990, April-26-1994, May-13-1995) over the Midwest. Chi-square, Nearest Neighbor, and Point Density calculations were performed and suggest that lightning polarity/frequency shift between soil moisture classes at a = .01. Using lightning characteristics in the thunderstorm lifecycle, one is able to evaluate relative tornadogenesis areas within moisture classes some 8-10 hours in advance. Tornadogenesis points fell within expected areas indicating that borders between marginal and small moisture classes are approximate locations of stage change (mature to dissipation) of the thunderstorm lifecycle. Results are intended to be used as a tool that helps verify situations that are more likely to be tornadic when observing real-time lightning data from thunderstorms crossing significant soil moisture boundaries. / Department of Geography

In the wildfire community fuel moisture content (FMC) is the quantity of choice when it comes to assess vegetation water status in relation to fire risk and fire behaviour. Field measurements of FMC are both expensive and time consuming and, in addition, sampling is often spatially inadequate. Remote sensing could represent an almost ideal solution both in terms of spatial and temporal coverage, if a consistent relationship between FMC and spectral reflectance could be established. A review of the literature suggests that it is difficult to retrieve FMC for dense forest canopies with remote sensing platforms. This study took a step back and explored the relationship between spectral reflectance and vegetation water content at the leaf level, where several confounding factors present at the canopy level are eliminated or controlled for. It also considered a conifer species, because relatively little research has been produced on this topic for this type of vegetation. The main goal was to establish if FMC can be derived directly from spectral reflectance in the solar spectrum using two well known approaches, such as spectral indices and continuum removal. It is also aimed at exploring if an alternative, indirect way to measure FMC as ratio of Equivalent Water Thickness (EWT) and Specific Leaf Weight (SLW) is feasible and accurate. The results derived from Douglas-fir (Pseudotsuga menziesii (Mirb) Franco) needles used in this study suggested that FMC was not directly retrievable from spectral reflectance but vegetation water content could be assessed with sufficient accuracy in terms of EWT. Also the retrieval of SLW from reflectance of fresh foliage proved to be challenging. Finally, the study also highlighted several aspects in the relationships among foliar water content, dry matter content and reflectance that require additional research. / Graduate

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Typescript (photocopy) / xx, 251 leaves, [6] leaves of plates : ill. (part col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1982

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1982. / Includes bibliographical references (leaves 73-75).

Thesis (M.S. - Soil and Water Science)--University of Arizona, 1984. / Includes bibliographical references (leaves 63-66).